Where the reference voltage \(V_{N}\) is the nominal voltage at the low voltage side of the transformer and the rated apparent power \(S_{N}\) is defined system wide in the net object (see Unit Systems and Conventions).

On which side the reference voltage is adapted depends on the \(tp\_side\) variable:

tp_side=”hv”

tp_side=”lv”

\(V_{n, HV, transformer}\)

\(vnh\_kv \cdot n_{tap}\)

\(vnh\_kv\)

\(V_{n, LV, transformer}\)

\(vnl\_kv\)

\(vnl\_kv \cdot n_{tap}\)

Note

The variables tp_min and tp_max are not considered in the power flow. The user is responsible to ensure that tp_min < tp_pos < tp_max!

Cross regulator

In addition to tp_st_percent a value for tp_st_degree can be defined to model an angle shift for each tap, resulting in a cross
regulator that affects the magnitude as well as the angle of the transformer ratio.

Ideal phase shifter

If tp_phase_shifter is set to True, the tap changer is modeled as an ideal phase shifter, meaning that a constant
angle shift is added with each tap step: